Police used tear gas or pepper spray on protesters and Saakashvili appeared on the roof of the building during the drama, shaking his fist and accusing Poroshenko of being a traitor and a thief before being dragged away by security forces.

As the events unfolded in the street, Prosecutor-General Yuriy Lutsenko alleged at a briefing that an "organized crime" group led by Yanukovych, who is in exile in Russia, have financed protests organized by Saakashvili.

Saakashvili's detainment prompted clashes between law enforcement officers in riot gear and supporters of the former Georgian president, who urged "all Ukrainians to take to the streets and drive out the thieves."

"Do not let lawlessness happen. Do not let chaos happen. Do not let Poroshenko and his gang continue the robbery," he said.

"Ukraine is under a real threat. These people have completely usurped power."

Shouting and shoving matches ensued, and after police hauled Saakashvili into a blue van, supporters attempted to lie in the street to keep him from being taken away.

Hours later, more than 1,000 supporters were on the scene, along with dozens of police, and cars were wedged close together in an effort to keep the van from moving away.

The street was blocked with a makeshift barricade.

The commotion began shortly after 7 a.m. and was first made public by Saakashvili associate David Sakvarelidze.

"They're breaking down the door at Mikheil Saakashvili's home!" he wrote on Facebook, giving the address and apartment number.

The Ukrainian Security Service (SBU) said that Saakashvili’s residence was being searched as part of a criminal inquiry conducted by the Prosecutor General’s Office.

Hitlyanska did not specify the nature of the criminal inquiry, but the SBU later said Saakashvili was accused of "complicity with members of criminal organizations and concealing their activity by providing premises and by other means."

At a news briefing, Lutsenko alleged that Saakashvili has held protests financed by allies of Yanukovych, who was pushed from power by pro-European protests in February 2014 and fled to Russia.

The prosecutor-general said the alleged Yanukovych allies included Serhiy Kurchenko, a businessman who also fled to Russia, and claimed that Saakashvili had received $500,000 in a bank transfer from Russia.

As the search unfolded, live videos shared on social media showed a chaotic and sometimes violent scene outside Saakashvili’s building, steps away from Kiev’s Maidan Nezalezhnosti, or Independence Square -- the focal point of the Euromaidan protests.

A shoving match between law enforcement agents and supporters of Saakashvili ensued as the latter tried to push their way into the apartment.

Saakashvili appeared on the roof, and officers quickly seized him and moved him away from the ledge before bringing him out of the building.

Video on Facebook showed dozens of riot police around the apartment building preventing people from entering.

The search of Saakashvili's home was conducted two days after his Movement of New Forces party organized a rally in Kiev calling for Poroshenko's impeachment and for legislation that would allow it to take place.

Poroshenko has accused the protest organizers of seeking to destabilize Ukraine, which is struggling with economic troubles and a deadly conflict with Russia-backed separatists in two eastern provinces.

Saakashvili was swept to power in Georgia's peaceful Rose Revolution in 2003 and served as president of Georgia from 2004-13.

He conducted major reforms and fought corruption in the former Soviet republic but was accused of abusing his power and is wanted in his home country on suspicion of trying to organize a coup there after leaving office, an allegation he denies.

In the wake of the Euromaidan protests that brought a pro-Western government to power in Ukraine, Poroshenko appointed Saakashvili -- an acquaintance from university days -- as governor of the Odessa region in 2015.

Saakashvili surrendered his Georgian citizenship to take the post.

But Saakashvili resigned in November 2016, saying his reform efforts had been blocked by Poroshenko’s allies, and went into the opposition.

Saakashvili was then stripped of Ukrainian citizenship by Poroshenko while he was in the United States in June 2017, a move he is challenging in court.

Weeks later, Saakashvili forced his way back into Ukraine and was found guilty of violating the state border.

He paid a fine and has since been touring the country, speaking out against Poroshenko and trying to garner support for his fledgling political party, Movement of New Forces.

Saakashvili has indicated he wants to be Ukraine’s next prime minister, a post that he could theoretically hold as it is a position appointed by the president upon ratification by parliament.

With his citizenship status in flux, under current law he is forbidden from officially running for president.

While well-known across Ukraine, Saakashvili and his party enjoy little public support, with nearly all polls showing putting them at around 1-2 percent.

Saakashvili recently claimed that Poroshenko was planning to force him to flee to another country to avoid extradition to Georgia.

During the rally on December 3, Saakashvili alleged in comments to Georgia’s Rustavi-2 television that Poroshenko and former Georgian Prime Minister Bidzina Ivanishvili have "agreed that a sentence on trumped-up charges will be quickly issued next week.”

Poroshenko’s office has not commented on the allegations or Saakashvili's detention on December 5.